(i read the title too quickly and saw it as "Napping before game...", which i immediately thought is better than napping during the game, but anyway...)
i like ExplodingWizard and Armadillo's suggestions a lot; i have taken recently to doodling lines curves and shapes in a sketch book and turning those abstract designs into maps. as far as scale is concerned, i scan them into photoshop clean them up, and print them onto 8 1/2" x 11" grid paper.
photoshop is also nice to use because you can edit fairly easily, use colors quickly, and print out a DM version and a non-keyed version (using hidden layers) for the players.
finally, another DM i used to game with would use city maps - the ones showing city blocks, streets, buildings, etc - trace over them, turning the buildings on the maps into rooms, the streets into corridors, parks into chasms or fungus gardens, etc.. kinda cool!